Data is commonly stored on magnetic disks in computer applications. These disks are divided into multiple concentric tracks and data is stored along these tracks as individual magnetized portions of the tracks. The disk drive unit uses multiple read/write heads to transmit data to and from the magnetic disks, and the characteristics of these heads determine overall drive efficiency. More efficient heads may write and read data more effectively, allowing greater data storage and easier retrieval.
A problem with read/write heads is that different heads in a single disk drive may be of varying qualities. A single head manufacturer may create heads which, while meeting specifications for reading and writing capacity, are not as efficient as other heads used in the same drive. Consequently, when using multiple heads having varying levels of effectivity, writing may take more time than anticipated, and a disk may store less data than if a head had greater effectiveness, or could handle data at a higher speed or with greater density of data. Further, if data is recorded using a head having excellent read/write capacities at a slower rate, data will not be stored on the disk although the capability to do so exists.
Past solutions to data transfer problems have been to increase the data transferred through the heads uniformly, as if all heads operated identically. The problem with these methods, as outlined above, is that variations in head quality cause data transfer problems, decreasing yields for the entire head disk assembly (HDA).